From c22ca4a96300c8ed01fe2282d2dd9e9a75032379 Mon Sep 17 00:00:00 2001 From: "Vishal Moola (Oracle)" Date: Tue, 3 Mar 2026 11:48:24 -0800 Subject: [PATCH 1/4] x86/mm/pat: Convert pte code to use page table apis Use the ptdesc APIs for all page table allocation and free sites to allow their separate allocation from struct page in the future. Convert the PTE allocation and free sites to use the generic page table APIs, as they already use ptdescs. Pass through init_mm since these are kernel page tables; otherwise, pte_alloc_one_kernel() becomes a no-op. Signed-off-by: Vishal Moola (Oracle) Signed-off-by: Dave Hansen Acked-by: Mike Rapoport (Microsoft) Link: https://patch.msgid.link/20260303194828.1406905-2-vishal.moola@gmail.com --- arch/x86/mm/pat/set_memory.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 40581a720fe8..a4b1b329c23d 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -1408,7 +1408,7 @@ static bool try_to_free_pte_page(pte_t *pte) if (!pte_none(pte[i])) return false; - free_page((unsigned long)pte); + pte_free_kernel(&init_mm, pte); return true; } @@ -1539,7 +1539,7 @@ static void unmap_pud_range(p4d_t *p4d, unsigned long start, unsigned long end) static int alloc_pte_page(pmd_t *pmd) { - pte_t *pte = (pte_t *)get_zeroed_page(GFP_KERNEL); + pte_t *pte = pte_alloc_one_kernel(&init_mm); if (!pte) return -1; From 6ba1917a4c5c59415c8fc3f83019d92e3f81c87c Mon Sep 17 00:00:00 2001 From: "Vishal Moola (Oracle)" Date: Tue, 3 Mar 2026 11:48:25 -0800 Subject: [PATCH 2/4] x86/mm/pat: Convert pmd code to use page table apis Use the ptdesc APIs for all page table allocation and free sites to allow their separate allocation from struct page in the future. Convert the PMD allocation and free sites to use the generic page table APIs, as they already use ptdescs. Pass through init_mm since these are kernel page tables, as pmd_alloc_one() requires it to identify kernel page tables. Because the generic implementation does not use the second argument, pass a placeholder to avoid reimplementing it or risking breakage on other architectures. Signed-off-by: Vishal Moola (Oracle) Signed-off-by: Dave Hansen Acked-by: Mike Rapoport (Microsoft) Link: https://patch.msgid.link/20260303194828.1406905-3-vishal.moola@gmail.com --- arch/x86/mm/pat/set_memory.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index a4b1b329c23d..72a260007996 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -1420,7 +1420,7 @@ static bool try_to_free_pmd_page(pmd_t *pmd) if (!pmd_none(pmd[i])) return false; - free_page((unsigned long)pmd); + pmd_free(&init_mm, pmd); return true; } @@ -1549,7 +1549,11 @@ static int alloc_pte_page(pmd_t *pmd) static int alloc_pmd_page(pud_t *pud) { - pmd_t *pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL); + /* + * Pass 0 as a placeholder for the second argument, since the + * generic implementation of pmd_alloc_one() does not use it. + */ + pmd_t *pmd = pmd_alloc_one(&init_mm, 0); if (!pmd) return -1; From b2203a9bf53237368a7c7fc976c9616b5562af8e Mon Sep 17 00:00:00 2001 From: "Vishal Moola (Oracle)" Date: Tue, 3 Mar 2026 11:48:26 -0800 Subject: [PATCH 3/4] x86/mm/pat: Convert populate_pgd() to use page table apis Use the ptdesc APIs for all page table allocation and free sites to allow their separate allocation from struct page in the future. Convert the remaining get_zeroed_page() calls to the generic page table APIs, as they already use ptdescs. Pass through init_mm since these are kernel page tables, as both functions require it to identify kernel page tables. Because the generic implementations do not use the second argument, pass a placeholder to avoid reimplementing them or risking breakage on other architectures. It is not obvious whether these pages are freed. Regardless, convert the remaining free paths as needed, noting that the only other possible free paths have already been converted and that a frozen page table test kernel has not reported any issues. Signed-off-by: Vishal Moola (Oracle) Signed-off-by: Dave Hansen Acked-by: Mike Rapoport (Microsoft) Link: https://patch.msgid.link/20260303194828.1406905-4-vishal.moola@gmail.com --- arch/x86/mm/pat/set_memory.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 72a260007996..17c1c28e3491 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -1747,7 +1747,11 @@ static int populate_pgd(struct cpa_data *cpa, unsigned long addr) pgd_entry = cpa->pgd + pgd_index(addr); if (pgd_none(*pgd_entry)) { - p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL); + /* + * Pass 0 as a placeholder for the second argument, since the + * generic implementation of p4d_alloc_one() does not use it. + */ + p4d = p4d_alloc_one(&init_mm, 0); if (!p4d) return -1; @@ -1759,7 +1763,11 @@ static int populate_pgd(struct cpa_data *cpa, unsigned long addr) */ p4d = p4d_offset(pgd_entry, addr); if (p4d_none(*p4d)) { - pud = (pud_t *)get_zeroed_page(GFP_KERNEL); + /* + * Pass 0 as a placeholder for the second argument, since the + * generic implementation of pud_alloc_one() does not use it. + */ + pud = pud_alloc_one(&init_mm, 0); if (!pud) return -1; From e751303e0ad2e998f421d104193f6904df3516d1 Mon Sep 17 00:00:00 2001 From: "Vishal Moola (Oracle)" Date: Tue, 3 Mar 2026 11:48:27 -0800 Subject: [PATCH 4/4] x86/mm/pat: Convert split_large_page() to use ptdescs Use the ptdesc APIs for all page table allocation and free sites to allow their separate allocation from struct page in the future. Update split_large_page() to allocate a ptdesc instead of allocating a page for use as a page table. Signed-off-by: Vishal Moola (Oracle) Signed-off-by: Dave Hansen Acked-by: Mike Rapoport (Microsoft) Link: https://patch.msgid.link/20260303194828.1406905-5-vishal.moola@gmail.com --- arch/x86/mm/pat/set_memory.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 17c1c28e3491..cba907c39718 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -1119,9 +1119,10 @@ static void split_set_pte(struct cpa_data *cpa, pte_t *pte, unsigned long pfn, static int __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, - struct page *base) + struct ptdesc *ptdesc) { unsigned long lpaddr, lpinc, ref_pfn, pfn, pfninc = 1; + struct page *base = ptdesc_page(ptdesc); pte_t *pbase = (pte_t *)page_address(base); unsigned int i, level; pgprot_t ref_prot; @@ -1226,18 +1227,18 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, static int split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address) { - struct page *base; + struct ptdesc *ptdesc; if (!debug_pagealloc_enabled()) spin_unlock(&cpa_lock); - base = alloc_pages(GFP_KERNEL, 0); + ptdesc = pagetable_alloc(GFP_KERNEL, 0); if (!debug_pagealloc_enabled()) spin_lock(&cpa_lock); - if (!base) + if (!ptdesc) return -ENOMEM; - if (__split_large_page(cpa, kpte, address, base)) - __free_page(base); + if (__split_large_page(cpa, kpte, address, ptdesc)) + pagetable_free(ptdesc); return 0; }